I cam across the idiom:
zur Frau werden - to become a woman
I'm wondering what does it really mean. In what sense to become a woman?
The place where I would expect this idiom is a (romantic) novel where a usually male protagonist leaves a place, returns after several years and finds that the child he was used to percieve is now an adult attractive female.
I don't think it is used in a strictly biological sense (referring to sexual maturity), since I never noted it's usage in that context, but I may be wrong here.
In general I'd say it is more a change in how a woman is percieved, usually by men, than an actual change of the woman in question. It may also describe an instantaneous change. I would not expect to hear it in every day speech.
It obviously depends on the context, but my guess would be it either means going through puberty and growing breasts etc., or losing one's virginity.
In any case, it is very probably about the transformation from a child to an adult (maybe only in certain specific aspects), and something specifically female. I don't really think this is a language question, but more of a cultural one.
In contemporary German "zur Frau werden" has the same meaning as the English idiom
A girl becomes a woman
meaning the transisition from a girl (Mädchen) to a woman (Frau).
There is no fixed time point for this, i.e. unlike in other cultures there are no initiation rites involved but we do have some legislative on this, namely the age when a female is allowed to marry (Ehemündigkeit) set to 16. As was said before common sense puts this point at the end of puberty.
Earlier in history there also was an intermediate state when "Frau" was used mainly for a married woman. An unmarried woman was entitled "Fräulein" (see also this question).
Another connotation from "eine Frau werden" used mainly in literature (or in prudish texts) may also be the loss of innocence. This connotation can also be found for a male ("ein Mann werden").
It is fine lines, but this might all be a bit sexist, I am afraid. I think women and men are treated differently.
Question is though, wether the speakers do know that themselves, so the context might be more important than the actual words used.